Metrohm Vision Manual - Manual (Page 24)

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The constituent name “plasticizer” was added. Next, enter the units, and decimal points to be
displayed. In this case, “2” is entered, to display 2 digits after the decimal point. Click on OK.
This procedure holds for the first sample saved in a product. When next samples are saved, Vision
assumes the same product, class, and constituent configuration as for the previous sample.
Alternatively, the user may enter new information, to create a new product during the session.
3.3.3 Using the Stored Reference
Vision allows a reference scan to be saved and retrieved later. This is not the normal procedure, as
the stored reference can contribute to spectral inaccuracy, under some conditions. Consult Metrohm
NIRSystems before implementation of a Stored Reference.
• Click on Acquire/Store Reference to save the last taken reference spectrum.
• In the Store Reference window, enter the reference name and click on OK.
• To retrieve a stored reference, click on Acquire/Select Reference. In the Select Reference
window, highlight the name of the reference you want to use and click on Load. The loaded
reference will be the active reference until you acquire or load a new one.
3.3.4 Using the External Reference
The External Reference feature in Vision allows for correction for the fiber length or fiber
characteristics on a 6500-Series Process instrument. It is highly recommended for use in all 6500-
Series process instruments. (XDS Process Instruments use Reference Standardization instead.)
In normal data acquisition, the reference spectrum (in the log(1/R) form) is subtracted from the
analogous form of the sample spectrum, resulting in the absorbance spectrum. This standard
approach works very well for instruments for which the reference light path (channel) is identical to
the sample light path (channel), most often laboratory systems.